Editing Infection (section)

====Contagiousness====
Infectious diseases are sometimes called [[contagious disease]]s when they are easily transmitted by contact with an ill person or their secretions (e.g., [[influenza]]). Thus, a contagious disease is a subset of infectious disease that is especially infective or easily transmitted. All contagious diseases are infectious, but not vice versa.<ref>{{cite web|url=https://equine.ca.uky.edu/content/science-sleuths-science-shapes-diagnostic-tests-infectious-or-contagious-%E2%80%93-which-it|title=Science Sleuths: the Science that Shapes Diagnostic Tests: Infectious or Contagious – Which Is It?|publisher=Ag Equine Programs|access-date=2025-01-03}}</ref><ref>{{cite web|url=https://www.britannica.com/dictionary/eb/qa/The-Difference-between-Contagious-and-Infectious-|title=The Difference between 'Contagious' and 'Infectious'|publisher=Britannica}}</ref> Other types of infectious, transmissible, or communicable diseases with more specialized routes of infection, such as vector transmission or sexual transmission, are usually not regarded as "contagious", and often do not require medical isolation (sometimes loosely called [[quarantine]]) of those affected. However, this specialized connotation of the word "contagious" and "contagious disease" (easy transmissibility) is not always respected in popular use.

Infectious diseases are commonly transmitted from person to person through direct contact. The types of direct contact are through person to person and [[respiratory droplet|droplet spread]]. Indirect contact such as airborne transmission, contaminated objects, food and drinking water, animal person contact, animal reservoirs, insect bites, and environmental reservoirs are another way infectious diseases are transmitted. The [[basic reproduction number]] of an infectious disease measures how easily it spreads through direct or indirect contact.<ref>Higurea & Pietrangelo 2016 {{page needed|date=August 2020}}</ref><ref>{{cite web|url=https://globalhealth.harvard.edu/understanding-predictions-what-is-r-naught/|title=Understanding Predictions: What is R-Naught?|publisher=Harvard|date=February 7, 2020}}</ref>